Control and design of DC grids for offshore wind farms

Recently, the interest in offshore wind farms has been increased significantly. Besides the huge amount of space available, they have the advantage of an increased and more constant wind speed, leading to a higher and more constant production of power. Although, a lot of mechanical problems for constructing these farms have been solved during the past decade, the electrification is still a major issue in research. For large wind farms situated more than 60 km from the shore, an HVdc connection is favorable. Consequently, a pure dc system could be an interesting and cost-effective solution for offshore wind farms. In this paper, a control structure for such a dc grid is presented and analyzed. Furthermore, different configurations are compared and the developed simulation models are presented.